Cannon pinion assembly



P 1960 H. IQUEGER 2,952,118

CANNON PINION ASSEMBLY Filed June 11, 1956 FIGJ INVENTOR Herman Rucqnr FIG. 4 I] ATTORNEY United States Patent CANNON PINION ASSEMBLY Herman Rueger, Lancaster Township, Lancaster County, Pa., assignor to Hamilton Watch Company, Lancaster, Pa., a corporation of Pennsylvania Filed June 11,1956, Ser. No. 590,552

3 Claims. c1. 58-138) This invention'relates to the cannon pinion of a clock or watch, and more particularly that type of clock or watch which is operated by a battery and has a balance wheel and hairspring assembly.

The object of the present invention is to provide means for driving the hour, minute and second hands which will be as friction free as possible, and yet render them capable of being set through the ordinary means of stem setting.

In watches or clocks in which the power comes from an oscillating wheel, in contrast to a spring driven clock where the oscillating wheel merely controls the escape of power, it is necessary to have several drives as frictionless as possible in order that a source of power as small as possible may be used. It is due to this limitation of power, in the form of a battery small enough to fit within the clock or watch, that makes such a construction desirable. In the ordinary arrangement the cannon pinion provides a friction drive which under the action of the setting stem will slip and allow the minute and hour hands to be set. This is a good arrangement where there is a large source of power for driving the center arbor, but where that power is limited and the torque used to drive the center arbor is very small the tolerances necessary to maintain the exact degree of friction which will permit the driving of the minute and hour hands by the center arbor and yet permit slippage when it is necessary to set these hands and without danger to the train, are so small that the manufacturing problem is very great.

The object of this present invention is to provide a substitute for the cannon pinion which will provide a drive which has less friction, and which may be quickly and easily set by movement of the stem in the ordinary manner.

It is a further object of the present invention to provide a very thin resilient washer which may be distorted so as to exert a pressure between two interworking surfaces, the friction drive being dependent on the resiliency of the washer which may be easily determined and easily manufactured.

The invention is shown in the accompanying drawing in which:

Figure 1 is a vertical cross section of the center staff and attached hand driving mechanism, the parts being shown in spaced position.

Figure 2 is a view similar to Figure 1 with the parts in working position.

Figure 3 is a cross section of the cannon pinion assembly in inoperative position.

Figure 4 is a plan View of the assembly, actual size.

In the drawings the center staff is shown at 8 as being journalled in a bearing 10 in the upper bridge 12. It is also supported by the lower bridge 14. The center stall and its pinion are preferably formed of a single piece having an integral pinion 18 which is in mesh with the fourth wheel, not shown. The fourth wheel is driven (in an electric watch) by the indexing wheel which in turn is driven by the oscillating balance wheel. This 2,952,118 Patented Sept. 13, 1960 ice particular structure does not produce the torque on the fourth wheel that would ordinarily be there in a spring driven watch.

A center arbor 20 is formed with a shoulder 22 at its central portion which contacts the pillar plate 16. One end of the arbor is journalled at 24 in the lower bridge 14 and the other end terminates just beyond the dial 25 at 26. A center wheel 28 is mounted on and drives the central arbor 20. The center staff 8 turns freely on the central arbor and has mounted on its extreme end the second hand 30.

A sleeve 32 is frictionally supported by the lower end of the central arbor and rotates with the central arbor. This sleeve is formed with a substantially conical shaped head 34. Slidably mounted on the sleeve 32 is a cannon pinion 36 which has the usual elongated barrel and is formed at the pinion head with a conical depression 38 adapted to fit the conical head 34 of the sleeve 32. Carried between the conical depression 38 of the cannon pinion and the conical shaped head 34 of the sleeve is a resilient relatively flat washer 40. A hollow plug 42 fits slidably over the end of the center staff 8 and is frictionally held against the inner surface of the sleeve 32. In the assembly the plug 42 is forced inward along the center staff 8 and held tight against the inner side of the sleeve 32, forcing the conical shaped depression 38 of the cannon pinion 36 toward engagement with the conical shaped head 34, shaping the washer 40 into the form shown in Figure 2, the resiliency of the washer 40 being overcome by the friction fit between the plug 42 and the sleeve 32. It will be thus seen that the torque of the central arbor 20 transferred to the sleeve 32 will be in turn transferred to the cannon pinion 36 through the resiliency of the washer 40. This resiliency can be calculated and continually duplicated so that the cannon pinion is substantially free to turn with the movement of the central arbor, but there is still suflicient resistance to permit setting of the hands without affecting the train.

What is claimed is:

1. A cannon pinion assembly for watch movements having a centrally driven tubular arbor and a center staff within said arbor, comprising a sleeve frictionally fitting and driven by said arbor, said sleeve having a conical head, a cannon pinion overlying and loosely fitted on said sleeve, said cannon pinion further formed with a conical depression interfitting with the conical head of said sleeve, a resilient washer freely carried between the conical head of said sleeve and the conical depression of said cannon pinion, and a hollow plug frictionally engaging said sleeve and abutting the end of said cannon pinion for holding said resilient washer in a stressed condition between the conical depression of said cannon pinion and the conical head of said sleeve to provide resilient driving means between said sleeve and said cannon pinion through said resilient washer.

2. A cannon pinion assembly for watch movements having a centrally driven tubular arbor and a center staff within said arbor, comprising a sleeve frictionally fitting and driven by said arbor, said sleeve having a conical head, a cannon pinion overlying and loosely fitted on said sleeve, said cannon pinion further formed with a conical depression inter-fitting with the conical head of said sleeve, a resilient washer freely carried between the conical head of said sleeve and the conical depression of said cannon pinion, and means for holding said resilient washer in a stressed condition between the conical depression of said cannon pinion and the conical head of said sleeve to provide resilient driving means between said sleeve and said cannon pinion through said resilient washer, said means for holding said washer in a stressed condition also serving as a guide for the center staff.

3. A cannon pinion assembly for watch movements having a centrally driven tubular arbor and a center staff extending completely through said arbor, comprising a sleeve frictionally fitting and driven by said arbor, said sleeve having a conical head, a cannon pinion overlying and loosely fitted on said sleeve, said cannon pinion further formed with a conical depression interfitting with a conical head of said sleeve, a resilient Washer freely carried between the conical head of said sleeve and the conical depression of said cannon pinion, and means engageable with the end of said cannon pinion and slidably fitting over the end of said center stafi for holding said resilient washer in a stressed condition between the conical depression of said cannon pinion and the conical head of said sleeve to provide resilient driving means between said cannon pinion and said sleeve through said resilient washer.

References Cited in the file of this patent UNITED STATES PATENTS 

